<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script src="js/jquery-3.6.0.js" type="text/javascript"></script>
		<style type="text/css">
			.bc {
				background-color: orange;
			}
		</style>
	</head>
	<body>
		<form action="">
			用户名:<input type="text" name="username" value="" />
			<hr>
			密码:<input type="password" name="userpwd" />
			<hr>
			邮箱:<input type="email" name="useremail" disabled="disabled" />
		</form>
		<script type="text/javascript">
			// $("input[name='username']").addClass("bc");
			// $("input[name='username']").val("张三");
			// $("input[name!='username']").val("李四");
			
			
		</script>
	</body>
</html>
